Thin Film Bulk Acoustic Resonator (FBAR or TFBAR) is a device including a piezoelectric material sandwiched between two electrodes and acoustically isolated from the surrounding medium. FBAR devices using piezoelectric films with thicknesses ranging from several micrometers down to tenths of micrometers resonate in the frequency range of roughly 100 MHz to 10 GHz. Aluminum nitride and Zinc oxide are two common piezoelectric materials used in FBARs.
FBAR devices, including Bulk Acoustic Wave (BAW) filters, may be formed and subsequently attached to a substrate or circuit board using, e.g., flip chip techniques. Alternatively, FBAR devices, including BAW filters, may be incorporated into an integrated circuit (IC) chip at the wafer level, e.g., during CMOS (complementary metal oxide semiconductor) processing. The latter approach, i.e., forming FBAR devices at the wafer level during CMOS processing, eliminates the need for additional chips. However, tuning FBAR devices at the wafer level during CMOS processing is difficult due at least in part to the fabrication scale on monolithic devices.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.